"One of the things we find in studying drug exposures in pregnancy is that, because up to 50 percent of pregnancies are unplanned, women may be taking a medication and become pregnant while still taking a potentially harmful drug," says William Cooper. (Credit: Trevor/Flickr)

Women who take meds for autoimmune diseases during the first trimester of pregnancy are likely not putting their babies at significantly increased risk, a new study shows.

“This study is important because these conditions affect nearly 4.5 million persons in the US, including many women of childbearing age,” says first author William Cooper, professor of pediatrics and health policy at the Monroe Carell Jr Children’s Hospital at Vanderbilt University.

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“Currently, there are almost no data to guide women who are pregnant, or planning to become pregnant, who may need to continue their medications during pregnancy.”

The study, published in the journal Arthritis and Rheumatism, is one of the first to describe risks for medications used to treat autoimmune diseases when taken during pregnancy.

The three geographically diverse health plans collectively provide coverage for more than 8 million persons each year.

The cohort included 608 infants, including 437 with exposure during pregnancy and 171 whose mothers filled prescriptions for immunosuppressives before, but not during, pregnancy.

Women with rheumatoid and psoriatic arthritis, ankylosing spondylitis, lupus, scleroderma, and inflammatory bowel disease who filled prescriptions for immunosuppressive treatments during pregnancy were included in the study.

The drugs studied included hydroxychloroquine, tumor necrosis factor (TNF) inhibitors, and other immunosuppressives such as sulfasalazine and azathioprine.

When compared with the women who had medication treatment before, but not during pregnancy, the risk ratios for adverse fetal outcomes associated with immunosuppressive use during pregnancy were not statistically significant, the authors report.

Cooper says some of the medications in the study are relatively new and therefore haven’t been extensively used in pregnancy. As use continues to expand, follow-up studies will be important to ensure that new safety signals aren’t detected.

“One of the things we find in studying drug exposures in pregnancy is that, because up to 50 percent of pregnancies are unplanned, women may be taking a medication and become pregnant while still taking a potentially harmful drug,” Cooper says. “Therefore, it’s very important for women who have conditions that require medical treatments to talk with their providers about potential risks of medications in pregnancy.”

The National Institute of Arthritis and Musculoskeletal and Skin Diseases, Agency for Healthcare Research and Quality, the Food and Drug Administration, and the Safety Assessment of Biologic Therapy collaboration funded the study.